1. Technical Field
The present disclosure relates to a nonvolatile memory device and a method of fabricating the nonvolatile memory device and, more particularly, to a nonvolatile memory device capable of a stable operation and a method of fabricating the nonvolatile memory device.
2. Discussion of Related Art
Semiconductor memory devices are storage devices that can read stored data when needed, and are generally classified into RAM (Random Access Memory) and ROM (Read Only Memory). RAM is a volatile memory device, that is, stored information are lost when power is removed, whereas ROM is a nonvolatile memory device, that is, it retains stored information even when power is removed. The nonvolatile memory device includes, for example, PROM (Programmable ROM), EPROM (Erasable PROM), EEPROM (Electrically EPROM), or a flash memory device.
Nonvolatile memory devices are further classified into a NAND type and a NOR type in accordance with the structure of a cell array. While the NAND-type memory device is suitable for a high level of integration, the NOR-type memory device has the advantage of being able to rapidly process information. As a chip size becomes reduced, however, it is necessary to form the NOR-type memory device having the high integration.
For this reason, a split gate-type nonvolatile memory device is proposed. The split gate-type nonvolatile memory device is configured such that a word line is formed along a side wall from the upper part of a floating gate. Nevertheless, even in the split gate-type nonvolatile memory device, the decrease of the integration has been continuously required due to a decrease of the design rule.
Furthermore, the conventional split gate-type nonvolatile memory device forms a source region and a drain region by injecting ions, after forming both the floating gate and the control gate. Accordingly, the interface between the control gate and the floating gate or an inter-gate insulating film is exposed during the ion injection process. That is, the memory device is damaged by the ion injection process in which a high voltage is used, and the reliability of the memory device may be decreased.
If the reliability of the memory device is deteriorated, the program and erasing operations of the nonvolatile memory device may be not normally performed.